/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.i18n;

import org.springframework.context.i18n.LocaleContext;
import org.springframework.context.i18n.TimeZoneAwareLocaleContext;
import org.springframework.lang.Nullable;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;
import java.util.TimeZone;

/**
 * {@link org.springframework.web.servlet.LocaleResolver} implementation
 * that always returns a fixed default locale and optionally time zone.
 * Default is the current JVM's default locale.
 *
 * <p>Note: Does not support {@code setLocale(Context)}, as the fixed
 * locale and time zone cannot be changed.
 *
 * @author Juergen Hoeller
 * @see #setDefaultLocale
 * @see #setDefaultTimeZone
 * @since 1.1
 */
public class FixedLocaleResolver extends AbstractLocaleContextResolver {

    /**
     * Create a default FixedLocaleResolver, exposing a configured default
     * locale (or the JVM's default locale as fallback).
     *
     * @see #setDefaultLocale
     * @see #setDefaultTimeZone
     */
    public FixedLocaleResolver() {
        setDefaultLocale(Locale.getDefault());
    }

    /**
     * Create a FixedLocaleResolver that exposes the given locale.
     *
     * @param locale the locale to expose
     */
    public FixedLocaleResolver(Locale locale) {
        setDefaultLocale(locale);
    }

    /**
     * Create a FixedLocaleResolver that exposes the given locale and time zone.
     *
     * @param locale   the locale to expose
     * @param timeZone the time zone to expose
     */
    public FixedLocaleResolver(Locale locale, TimeZone timeZone) {
        setDefaultLocale(locale);
        setDefaultTimeZone(timeZone);
    }


    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        Locale locale = getDefaultLocale();
        if (locale == null) {
            locale = Locale.getDefault();
        }
        return locale;
    }

    @Override
    public LocaleContext resolveLocaleContext(HttpServletRequest request) {
        return new TimeZoneAwareLocaleContext() {
            @Override
            @Nullable
            public Locale getLocale() {
                return getDefaultLocale();
            }

            @Override
            public TimeZone getTimeZone() {
                return getDefaultTimeZone();
            }
        };
    }

    @Override
    public void setLocaleContext(HttpServletRequest request, @Nullable HttpServletResponse response,
                                 @Nullable LocaleContext localeContext) {

        throw new UnsupportedOperationException("Cannot change fixed locale - use a different locale resolution strategy");
    }

}
